Matsushita Electric Industrial Co., Ltd.

Nozomu Shinozaki

Shigeo Neki

Takashi Dohi

Takeshi Morofuji

Shinji Yamazaki

A sewing machine controlling apparatus which starts and stops a sewing machine or controls its speed in accordance with the position of an adjusting means, e.g. - control pedal, for setting a sewing machine speed. The sewing machine speed, as controlled by the controlling apparatus is independent of the influences caused by changes in the pedal position signal P.sub.A through the vibrations of the machine or through the variations in a power-supply voltage. A smooth speed switching operation, which is free from speed variations, can be realized even at a stepped switching point of the machine speed control pedal.

Sewing machine controlling apparatus

A speed setting arrangement for a sewing machine comprises a permanent magnet mounted for unitary rotation with the foot pedal of the sewing machine, and a magnetic sensor including a plurality of magnetoresistors arranged in pairs to form a bridge circuit on a stationary plane spaced a distance from the plane of rotation of the magnet. The magnetic sensor provides an output signal which is exclusively a function of the magnetic orientation of the magnet and thus serves as a valid indication of the amount of pedal depression. An analog to digital converter is coupled to the magnetic sensor to convert its output into a digital signal for speed control purposes.

Speed setting arrangement for sewing machines

A sewing machine controlling apparatus which starts and stops a sewing machine or controls its speed in accordance with the position of an adjusting means, e.g. control pedal, for setting a sewing machine speed, as speed. The sewing machine controlled by the controlling apparatus is independent of the influences caused by changes in the pedal position signal P.sub.A through the vibrations of the machine or through the variations in a power-supply voltage. A smooth speed switching operation, which is free from speed variations, can be realized even at a stepped switching point of the machine speed control pedal.

A sewing machine comprises a pedal position detector for detecting the position of the manually operated foot pedal of the machine and generating therefrom a pedal position indicating digital signal comprising a set of a predetermined number of binary digits. The sets of binary digits are organized into a plurality of command signals each comprising a plurality of sets of binary digits corresponding to adjacent positions of the pedal for indicating a specified operating condition of the sewing machine. The sewing machine is operated in response to the command signal.

Sewing machine having a digital command circuit

The circuit arrangement comprises a speed control system responsive to a speed signal indicative of the rotational speed of an arm shaft driving the sewing needle in the same manner as in known arrangements. Although the circuit arrangement operates in the same manner as in the known arrangement when a foot pedal is other than a neutral position, once the foot pedal is released to be in the neutral position, particularly provided speed setting data is used where the speed setting data value decreases as the rotational angle of the arm shaft increases. With this arrangement the sewing machine is capable of operating at a speed higher than conventional one during needle positioning with the speed being sufficiently reduced just before the needle is stopped. Thus a time length required for the last stitch has been remarkably reduced, providing efficient sewing work without deteriorating positioning accuracy. The sewing machine speed damping curve slope may be manually selected so that a user can set a desired positioning time. Furthermore, by selecting a needle position signal, the needle may be stopped at either at an uppermost position or a lowermost position.

Circuit arrangement for controlling sewing machine speed and for

Disclosed is a sewing machine having a tachogenerator for generating pulses at a frequency proportional to the speed of the sewing machine and a position detector for detecting the position of a foot pedal. A sewing condition detector is provided for detecting the operating conditions of the sewing machine in which it is to be subsequently operated and generating therefrom a corresponding condition indicating signal and a manually adjustable binary code generator for generating a speed indicating binary code in response to the condition indicating signal. Further included is a digital memory responsive to the position indicating signal and the speed indicating binary code for generating a speed control digital signal. The pulses generated by the tachogenerator are processed in accordance with the speed control digital signal to control the amount of motive power transmitted from a motor to the sewing machine.

Sewing machine having a memory for generating a speed signal in response

A speed setting device for an industrial sewing machine comprises a lever pivotally mounted at one end thereof on a stationary wall and adapted to be pivotally moved in response to the foot pedal of the sewing machine. An arm is pivotally mounted at one end to the stationary wall and operatively engaged with the lever so that they rotate in unison about respective pivot points thereof. The pivot point of the second member is between the lever pivot point and the engagement point between the lever and arm. Thereby, the arm is rotated through an angle greater than the angle through which the lever is rotated in response to the angular displacement of the foot pedal. An angular displacement sensor detects the angular displacement of the arm to generate a speed setting signal.

Speed setting device for a sewing machine

A sewing machine comprises a pedal position detector for detecting the position of a manually operated foot pedal and generating therefrom a pedal position indicating signal. A predetermined position of the armshaft of the sewing machine is detected for generating an armshaft position signal. A soft-start speed setting circuit is provided for successively generating a soft-start speed setting signal of an increasing value as a function of time in response to the occurrence of the armshaft position signal. The soft-start speed setting signal is enabled when it is smaller in magnitude than the pedal position indicating signal and conversely the pedal position indicating signal is enabled when the latter is smaller than the soft-start speed setting signal. The enabled signal is used to control the speed of the sewing machine.

Sewing machine having a soft-starting circuit

A needle position detector for a sewing machine includes a pair of disk-like members axially mounted on a rotary shaft coupled to the armshaft of the sewing machine. Each of the disk-like members is provided with an optically nonreflective portion occupying a greater area of its circumference and an optically reflective portion occupying a smaller area of the circumference. The disk-like members are adjusted so that the angular positions of the respective reflective portions correspond to the upper and lower needle positions. A light emitting element is associated with each of the disk-like members to emit light in a radial direction thereto. A light sensitive element is also associated with each disk-like member to receive light reflected from the reflective portion of the associated disk-like member to generate a needle position signal.

Needle position detector

A speed detector comprises a rotary shaft for rotation with a sewing machine, a ring-shaped permanent magnet uniformly magnetized in a direction parallel to the axis of the rotary shaft, at least one ring-shaped, internally toothed ferromagnetic member or stator and an externally toothed ferromagnetic circular member or rotor which is secured to the rotary shaft inside the stator to form a varying air gap between the opposing teeth. The permanent magnet and the two ferromagnetic members are disposed to form a closed loop magnetic circuit in which a ring-shaped coil is disposed. The air gap and hence the reluctance of the magnetic circuit changes periodically with the revolution of the rotary shaft so that a voltage is generated in the coil which varies at a frequency proportional to the operational speed of the sewing machine.

Speed detector for sewing machines

An electromagnetic clutch for use with a motor having a fixed bracket and a rotatable motor shaft which comprises a flywheel attached to the motor shaft and an output shaft rotatably supported by the bracket. A clutch rotor is attached to the output shaft so as to extend between the flywheel and a radial portion of the bracket. A clutch section is provided which includes a clutch ring axially movable with respect to the flywheel when a clutch solenoid is energized. A brake section is also provided which includes a brake ring axially movable with respect to the bracket when a brake solenoid is energized. Both the clutch and brake rings are mounted on sliding members which may be axially displaced relative to pins secured to the flywheel and bracket, respectively. Buffer members are interposed between the rings and sliding members.

Electromagnetic clutch and brake

An electric sewing machine driving apparatus includes a clutch coil of an electromagnetic clutch for transmitting a driving motor torque to a sewing machine, a brake coil of an electromagnetic brake for braking the sewing machine, a needle position signal generator for generating a signal indicative of a position where a needle of the sewing machine is to stop, a DC power supply for energizing the clutch coil and the brake coil, voltage generating means for generating a DC voltage higher than the supply voltage of the DC power supply and a capacitor disposed to be charged by the voltage generated by the voltage generating means, whereby an electric charge stored in the capacitor discharges through the brake coil in response to the needle position signal from the needle position signal generator, thereby improving the needle positioning accuracy of the sewing machine.

Electric sewing machine driving apparatus

A digital speed control system for a sewing machine comprises a digital speed setting device which responds to manual depression of a foot pedal by generating a digital position signal. A variable frequency divider divides the frequency of speed related pulses so that its output frequency is an integral submultiple of the input frequency, which is variable as a function of the digital position signal. A period detector senses the interval between pulses that occur successively at the output of the frequency divider and generates binary data representing the sensed interval. The interval representing data are translated into second period data in an arithmetic unit according to a predetermined transfer function. A pulse generator translates the second period data into a pulse for activating a magnetic clutch or a magnetic brake depending on the sign of the second period data to accelerate or decelerate the sewing machine.

Digital speed control system for sewing machines

A digital speed control system for a sewing machine comprises a digital speed setting device which responds to manual depression of a foot pedal by generating a digital position signal. A variable frequency divider divides the frequency of speed related pulses so that its output frequency is an integral submultiple of the input frequency, which is variable as a function of the digital position signal. A period detector senses the interval between pulses that occur successively at the output of the frequency divider and generates binary data representing the sensed interval. The interval-representing data is translated into a second period data in an arithmetic unit according to a predetermined transfer function. The arithmetic unit provides correction of the most recently sensed pulse interval according to the direction and amount of the deviation of the most recent pulse interval with respect to the preceding pulse interval, whereby the second period data is accordingly modified by an amount proportional to the rate of sewing speed variation. A pulse generator translates the second period data into pulse for activating a magnetic clutch or a magnetic brake depending on a sign of the second period data to accelerate or decelerate the sewing machine.

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Hirakata, Japan

Nozomu Shinozaki